A METHOD OF INK JET PRINTING WITH IMAGE QUALITY CONTROL

Description

FIELD OF THE INVENTION

[0001] The invention relates to inkjet printing and in particular to printing with curable inks.

BACKGROUND OF THE INVENTION

[0002] Inkjet printing is a well known in the art printing method. The basics of this technology are described, for example by Jerome L. Johnson «Principles of Nonimpact Printing », Palatino Press, 1992, Pages 302 - 336. ISBN 0-9618005-2-6. Commercial products such as computer printers, large format graphics printers and others exist.

[0003] An ink-jet print head consists of an array or a matrix of ink nozzles, with each nozzle selectively ejecting ink droplets. A given nozzle of the print head ejects the droplet in a predefined print position on the media. An assembly of the adjacently positioned on the media ink droplets creates a predetermined print pattern or image. Each image typically consists of multiple image elements such as pictorial or continuous tone elements, uniform tinted and solid elements, and line art and text elements. Color is another image element. Faithful reproduction of each image element is characterized by proper image sharpness, smoothness, spot size and other image quality parameters.

[0004] Inks used in the ink-jet printing industry are typically liquid solutions or emulsions. Known types of ink are oil-based inks, non-aqueous solvent-based inks, water-based inks, and solid inks. The deposited ink droplets are dried or cured. Recently, curing of ink by radiation and in particular ultraviolet (UV) radiation has become popular. In such cases, special radiation-curable ink is used and the image is cured by exposure to a curing radiation source. Typically, curing is performed by simultaneously irradiating all image elements with the same amount of curing radiation. The use of radiation-curable inks and the curing process are rapidly becoming an alternative to the established conventional drying process.

[0005] Curable ink must be cured within a short time period after it has been deposited on the substrate. Known prior art includes United States Patents No. 6,457,823; No. 6,561,640; No. 6,550,906 and United States Patent Application Publication No. 2004/0085423.

SUMMARY OF THE INVENTION

[0006] The invention provides a method and apparatus for improving printed image quality. The image quality improvement is achieved by differentially curing different image elements such as continuous tone elements, uniform tinted and solid elements, color elements, line art and text elements. A delay in the activation or variation in the intensity level of the curing radiation, duration of the image irradiation by the curing radiation or a mix of them that follows the ink droplet on substrate deposition, controls the ink droplet spread and accordingly the image quality. In the context of the present invention, image quality among others includes image banding reduction and image sharpness improvement. Banding is a phenomenon of clear visible irregular lines and stripes of a contrasting color that are not present in the digital image data.

[0007] According to the exemplary embodiments of the present invention, the quality improvement may be achieved by a method of ink jet printing with radiation curable ink, comprising ejecting droplets of ink onto a substrate to form an image, which includes one or more image elements such as continuous tone, uniform tinted and solid elements, color, line art and text image elements, and controlling the ink droplets spread magnitude by irradiating the image elements by curing radiation. The type of the image element irradiated sets the delay in the activation of the radiation source, the intensity level of the source, duration of the source operation and the profile of the intensity of the source or a mix of all or some of them.

[0008] In agreement with one exemplary embodiment of the method of the present invention the delay in the radiation source activation following the ink droplet ejection is determined by the type of the image element to be irradiated.

[0009] In agreement with another exemplary embodiment of the method of the present invention the type of the image element to be irradiated determines the intensity level of the radiation.

[0010] In agreement with a further exemplary embodiment of the method of the present invention the type of the image element to be irradiated determines the duration of the operation of the curing radiation source and the profile of the intensity of the curing radiation.

[0011] In agreement with the method of the present invention, the sources of the curing radiation are selected from a group of ultraviolet, visible or infrared radiation sources as the type of ink may require it.

[0012] According to the method of the present invention, the digital form (image data) of the type of image element to be printed controls the radiation source to provide the radiation only to printed portions of the respective image element.

[0013] The invention further provides a method of controlling image quality in ink jet printing. A method comprising depositing droplets of ink onto a substrate to form at least one row of pixels comprising different types of image elements, scanning with a scanning radiation beam the row of pixels and controlling the image quality by operating the radiation beam in agreement with the type of image element to be cured. The control of image quality is achieved by delaying the activation of the radiation beam, varying the intensity level of curing radiation and changing the profile of the intensity of the curing radiation as a function of the type of image element to be cured. The type of image element further sets the mix between the delay in the radiation source activation, duration of the radiation source operation, the intensity level of the source and the profile of the intensity.

[0014] The present invention provides an apparatus enabling implementation of the method of the present invention. The apparatus includes an ink jet print head for ejecting droplets of ink onto a substrate to form an image, which includes different types of image elements; a radiation emitting source to irradiate the image by radiation and a controller. The apparatus is characterized in that it includes a feature for analyzing the digital form of the image (image data) to be printed and operate the radiation source to differentially cure the ejected ink droplets.

[0015] According to the present invention the radiation source may move with the print head and the source may be a linear or two-dimensional array of individually addressable radiation sources as UV LEDs, Visible LEDs, UV or IR laser diodes. Alternatively, the radiation source may be a combination of UV and IR radiation sources. The radiation source may be or a combination of either UV or IR radiation sources only with each of them having different wavelengths. According to an additional embodiment, the radiation source may have a scanning laser beam.

[0016] Following the ink droplet deposition the radiation source provides the radiation at a delay determined by the type of the image element to be cured. The delay controls ink droplet spread and accordingly affects the image quality.

[0017] The image element to be cured further determines the duration of the radiation source operation. The duration of the radiation source operation controls ink droplet spread and accordingly affects the image quality.

[0018] Alternatively, the intensity level and the profile of the intensity provided by the radiation source may be varied and the type of the image element to be cured determines the variation in the radiation intensity. The variation in the radiation intensity level controls ink droplet spread and accordingly the image quality. Additionally, a mix of some or all of the source operational parameters such as the delay in the radiation source operation, together with the duration of the source operation, the intensity level of the radiation source and the profile of the intensity may be varied.

[0019] In agreement with the present invention, a feature for analyzing digital image analyzes the digital form of the image elements and determines the delay, duration, intensity level and the intensity profile of the radiation source operation. The feature, which is a combination of software and hardware, analyzes the digital image data and controls the operation of the radiation source.

[0020] The images printed by the apparatus of the present invention have better than images printed by conventional inkjet printing technique quality. The images exhibit less banding in continuous tone, uniform tinted and solid areas and are sharper than images printed by conventional inkjet printing techniques in text and line art areas. Practically, every image area containing a mix of image elements shows improvement in print quality.

[0021] The image quality is less dependent on the substrate properties since proper curing sequences controlling ink droplet spread or contraction may be selected for different substrates.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanied drawings, in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

Figures 1A and 1B (Prior Art) are simplified illustrations of a typical printed image and an inkjet printer.

Figure 2 is a schematic illustration of ink spreading on a wettable substrate.

Figure 3 is a schematic illustration of ink contraction on a non-wettable substrate.

Figure 4 is a schematic illustration of ink drop behavior at different time intervals following drop on substrate deposition.

Figure 5 is a schematic flow chart of the method of image quality improvement of the present invention.

Figures 6A - 6C are schematic illustrations of the delay in the radiation source activation for curing of different image elements, intensity variation and a combination of delay and intensity profile changes respectively according to the present invention.

Figure 7 is a schematic illustration of an inkjet printing apparatus constructed according to the present invention and an image printed by the apparatus.

Figure 8 is a schematic illustration of an inkjet printing apparatus with a scanning curing radiation source according to the present invention.

Figure 9 is a schematic illustration of magnified spot sizes of different image elements printed using differential curing timing according to the present invention.

Figure 10 is a schematic illustration of the operation of a curing radiation source according to the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODYMENTS

[0023] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods and procedures have not been described in detail so as not to obscure the present invention.

[0024] Some embodiments of the present invention are directed to curing of ink based on the type of image element of the printed image. The term "curing" throughout the specification and the claims refers to the process of converting a liquid such as, for example, ink to a solid by exposing it to curing radiation. According to some embodiments of the present invention, the curing radiation may be ultraviolet radiation and the ink used for printing may be ultraviolet curable ink. According to other embodiments of the present invention, the curing radiation may be infrared radiation and the ink used for printing may be infrared curable ink. According to additional embodiments, a combination of ultra violet and infrared radiation and respectively curable inks may be used.

[0025] Figure 1A is a simplified illustration of a typical prior art image printed on substrate 50 and a prior art inkjet printer. Each image usually consists of some image elements such as pictorial or continuous tone elements, uniform tinted and solid elements 52, line art 54 and text elements 56.

[0026] The image illustrated in Figure 1A is printed by a prior art inkjet printer that in its simplest form would have a multi nozzle inkjet print head 70, a controller or a Raster Image Processor (RIP) 74 and a radiation source 76, such as a conventional UV lamp operating in flash or continuous mode. Controller or RIP 74 may be such as a Personal Computer (PC) running appropriate software. During printing, print head 70 moves in the direction indicated by arrow 80 and ejects ink droplets 86 to cover according to the image data a print head wide strip 78 on substrate 50. Radiation source 76 may move together with print head 70 and may cure the ink droplets deposited onto substrate 50.

[0027] For bidirectional printing as indicated by arrow 80, a second radiation source 76, shown in phantom lines, may be mounted on the other side of print head 70. The printing may be performed in a mode where each print head path results in a strip of a single color (ink layer). Alternatively, each print head path may result in a strip including a number of colors (ink layers).

[0028] Print head 70 ejects ink droplets 86 of essentially the same volume. Adjacently positioned on the media ink droplets typically expand so, as to overlap and jointly cover certain area. As shown in Figure 1B each of the image elements mentioned are printed by the same spot size 84. The term "spot" designates the size (diameter or area) of the deposited on the substrate and cured ink droplet.

[0029] Controller 74 controls the operation and movement of inkjet print head 70 and may synchronize the operation of it with the movement of substrate 50 in the direction indicated by arrow 82. Radiation source 76 operates in flash or continuous operation mode to deliver an equal amount of radiation simultaneously to all types of image elements printed onto substrate 50.

[0030] Depending on the ink substrate interaction properties, when an ink droplet 90 is deposited on substrate 92 that has good wetting properties, as shown in Figures 2, the droplet will over some time expand and spread out to a spot 93 of a larger than droplet 92 size. In some instances that may involve poor wettable substrates 96, as shown in Figures 3, ink droplet 94 may contract to a spot 95 of a smaller than droplet 94 size. In one case there may be clear visible banding, especially in uniform areas and in the other case there may be blurred or discontinued fine image elements such as text and line art. A printed image in every portion of it usually includes a mix of elements and accordingly the quality of all of them is affected.

[0031] Figure 4 is a schematic illustration of ink drop behavior at different time intervals following droplet on substrate deposition. After deposition, if no curing radiation is applied to it, droplet 90 may continue to spread on substrate 92. The spot size formed by the droplet may have different diameter at each time interval and for the particular example described the relation of the spot diameter or surface area is S₀<S₁<S₂.

[0032] Printing with radiation curable ink provides an opportunity of controlling ink droplet spread differentially according to the type of the image element printed. The differential ink droplet spread and associated with it spot overlap control may be achieved by applying the curing radiation to different image elements at different time delays as shown in Figure 6A, which is a schematic illustration of differential curing of different image elements. The differential curing may be achieved; for example, by making the delay in the activation of the curing radiation source t₁ following ink droplet ejection for curing the text image element shorter than the delay t₃ in the operation of the curing radiation source for curing the continuous tone or uniform area image element.

[0033] Radiation source intensity level, duration of the irradiation of the image and profile of the irradiation intensity may also be used for differential control of ink droplet spread. The type of the image element to be irradiated (continuous tone, uniform solid etc.) may be used for setting the radiation intensity level, profile or duration. Figure 6B is a schematic illustration of differential curing different image elements where the radiation source intensity level is changed according to the image element to be cured. For example, the intensity of the curing radiation source I₃ for curing the text image element may be lower than the intensity I₁ of the curing radiation source for curing the continuous tone or uniform area image element.

[0034] Figure 6C is a schematic illustration of differential curing of different image elements where the radiation intensity profile is changed in a ramp form according to the image element cured. For example, the intensity of the curing radiation source I₃ for curing the text image element may start at a value higher than the intensity I₁ of the curing radiation source for curing the continuous tone or uniform area image element. In some cases, a mix of the intensity level, delay in activation of the radiation source, duration of the source operation or intensity profile may be present.

[0035] Printing by a droplet having larger spread or overlap allows reducing banding of continuous tone, uniform tinted and solid image elements. Droplets with larger spread or overlap mask the visible artifacts on uniform areas. Printing with droplets having smaller spread or overlap may allow increasing the sharpness of the text and line art image elements.

[0036] Figure 7 is a schematic illustration of an embodiment of an inkjet printing apparatus of the present invention and an image printed by the apparatus. The inkjet printing apparatus 98 may print with radiation curable ink. Print head 70 may eject droplets of ink 100 onto substrate 50 to form an image, which includes continuous tone, uniform tinted and solid areas 52, line art 54 and text 56 image elements. For the clarity of the explanation, the boundaries of each image element are schematically shown as rectangles bounded by phantom lines, although in practice different image elements are printed on common sections of the substrate.

[0037] Curing radiation source 116 cures ejected ink droplets. In one of the embodiments curing radiation source 116 may be a linear or two-dimensional array of individually addressable UV, Visible or IR Light Emitting Diodes (LED) or UV or IR lasers or laser diodes (collectively termed radiation emitters), depending on the type of ink used. Source 116 may be extended in the print head 70 scanning direction indicated by arrow 80 such as to enable sufficiently long delays and curing times of different image elements. Source 116 may have some image forming optics enabling irradiation of image sections as small as a single printed droplet or pixel spot size or any other spot size required.

[0038] In order to establish the required delay in the application of the curing radiation or the intensity of the curing radiation prior to printing or concurrently with the printing process the digital data of the image to be printed may be preprocessed as shown in Figure 5. Controller 74 that serves as a Raster Image Processor (RIP) may have a feature 72 for analyzing the digital image data to be printed. Feature 72 may be software operating on the controller or a combination of software and dedicated hardware. Feature 72 may scan the digital representation of the image (image data) to be printed (block 150) and divide it into print head wide strips (block 154). Each strip generally may contain continuous tone, line art and text elements, uniform tinted and solid elements as well as distinct color (for example, Pantone colors) areas to be printed.

[0039] The curing source operation may be adapted to the printing mode (block 156). Depending on the printing mode whether a strip of single color (ink layer) or a number of colors (ink layers) are printed simultaneously the emphasis may be placed: on the delay in the activation of the source; on the intensity level of the source; on the profile of the intensity of the source; on the duration of the irradiation of the printed image, or a mix of all or some of the above mentioned parameters. Accordingly, the most appropriate type of curing may be selected.

[0040] Feature 72 may identify all of the pixels belonging to a specific image element (block 158) and included in the particular image strip (block 154). Feature 72 may set for each image element the delay (Figure 6A) in radiation source activation following said ink droplet ejection (block 162) or droplet on substrate deposition. The delay in the activation of the radiation source may be determined by analyzing the digital data of the image element to be printed. The intensity level of the radiation source (block 166) may be set by analyzing the digital data of the image element to be printed. In a similar way, analyzing the digital data of the image element to be printed, feature 72 may set the profile of the intensity of the source (Figure 6C) and the duration of the irradiation of the printed image, or a mix of all or some of the above-mentioned parameters.

[0041] The digital data pertaining to the image element to be printed may directly control radiation source 116 (Figure 7) and operate the linear or two-dimensional array of radiation sources. In addition to this, the digital data may be used to provide the radiation only to printed portions of the respective image element. Image forming optics may be built to facilitate supply of the radiation to the printed droplets of the respective image element. The linear or two-dimensional array of radiation sources may be such radiation emitters as UV LEDs, Visible LEDs, UV or IR laser diodes. Alternatively, radiation source 116 may be a combination of UV and IR radiation sources. Source 116 may be a combination of UV (or IR) only radiation sources operating at different wavelengths. Both the print head and the radiation source may be on the same carriage and move together or each may have separate movement mechanism. In the case of a separate movement mechanism, the print head movement and the movement of the source may be synchronized.

[0042] In order to get proper curing it may be necessary to adjust in addition to the delay the intensity level of the radiation source (block 166), the profile of the intensity of the source, the duration of the irradiation action or all of the above together. Analysis of the digital data of the image element may set each of the parameters or a mix of them. Figures 6A - 6C respectively illustrate such cases. Following this, the printing process may begin and print head 70 prints first strip (block 170) and radiation source 116 cures it (block 172). The type of image element cured controls delay in the activation of radiation source 116 and the intensity of source 116 and if set other listed above parameters. Following completion of the first strip printing substrate 50 is advanced in direction of arrow 82 and the next strip is printed (block 174). Although the printing (block 170) and curing (block 172) are shown as sequential steps it possible to envision an apparatus structure where curing takes place almost simultaneously with printing.

[0043] In an alternative embodiment radiation source 116 may be replaced by a radiation source 126 (Figure 8) having one or more than one scanning laser beams 130. The scanning direction of beam 130 is across the array of pixels printed by each nozzle or orthogonal to the print head 70 movement direction 80. Both radiation source 126 and print head 70 may be placed on a common carriage 132. Alternatively, the laser sources may have independent drive systems. Depending on the type of ink used and power required it may be an UV laser, a LED or an IR laser diode (radiation emitters) with any scanning mechanism meeting the application requirements. Methods of varying or delaying scanning laser beam activation and/or the intensity of the beam, and/or the duration of the irradiation action as a function of the type of image element printed are similar to the disclosed above.

[0044] As schematically illustrated in Figure 7 the method of printing by ink droplets 100 having substantially identical volume may result in printing continuous tone, uniform tinted and solid image elements 52 with a spot size or overlap 108, shown in phantom lines, larger than the spot size (overlap) 110 of line art 54 and larger than spot size (overlap) 112 of text 56. It is necessary to mention that in a vast majority of cases two spot sizes, for example, one for continuous tone, uniform tinted and solid image elements and another one for line art could provide the desired improvement since the line art and text may be printed by a similar spot size.

[0045] Figure 9, which is a schematic illustration of magnified spot sizes of different image elements printed using differential curing according to the present invention, illustrates the differences in the overlaps in detail.

[0046] Figure 10 shows an exemplary embodiment of curing radiation source 116. Source 116 may be a linear or a two-dimensional array of individually addressable radiation emitters 140. Feature 72 (or controller 74) dedicated to the control of radiation source 116 may switch ON or OFF each of radiation emitters 140 setting the delay in the activation of an array and of each of radiation emitters 140, intensity level, intensity profile and irradiation action duration according to the digital image data processed by feature 72. The feature may identify all of the pixels belonging to a specific image element and included in the particular image strip. Controller 74 may set the intensity of each of radiation emitters 140 according to the digital image data processed by the feature or a mix of intensity and delay and duration of the irradiation process. For exemplary purposes only, source 116 is shown as including 10 (ten) linear arrays of radiation emitters 140. Arrow 146 indicates the print head movement direction. Alternatively, as shown by arrow 146' the substrate may move. In order to simplify the explanation drop ejection may occur, for example, at a time when first line 148 of radiation source passes over the corresponding line 148' of image 160 printed on substrate 50.

[0047] Hatched squares mark pixels of image 160 where droplets of ink were placed. Arrays 1, 2, 5, 6, 9 and 10 may cure corresponding printed image lines marked by similar tagged numbers of text or line art image and may have a delay schematically shown as two not operating radiation emitters 140 that pass over the printed image. (Slanted lines mark activated radiation emitters 144.) The delay in the operation of arrays 5, 6, 9 and 10 in addition to the required delay (two radiation emitters) includes the delay caused by their position on the substrate. Arrays 3, 4 and 7 may cure continuous tone or uniform tinted and solid art areas and may have a delay in their activation schematically shown as five non-operating radiation emitters. The delay in the operation of array 7 in addition to the required delay (five radiation emitters) includes the delay caused by its position on the substrate. Array 8 may be not operative and may be passing over image free area. Controller 74 synchronizes the delay, intensity, duration and profile or a mix of the delay, intensity, duration and profile in operation of each individual radiation emitter 140 with the type of image and image on substrate position.

[0048] The images printed by the method of the present invention have banding free continuous tone, uniform tinted and solid areas and much sharper text and line art images than images printed by conventional inkjet techniques.

[0049] The image quality is less dependent on the substrate since proper curing sequences controlling ink droplet spread or contraction may be selected for different substrates.

[0050] A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the scope of the invention.

Claims

1. A method of controlling printed image quality comprising ejecting droplets (100) of ink onto a substrate (50) to form a plurality of image elements (52,54,56) comprising image elements of at least two different types, said plurality of image elements forming an image; characterized that said ink droplets (100) spread is controlled by irradiating said image elements by a curing radiation, said curing radiation being controlled by operational parameters set based on the type of a given image element (52, 54, 56) to be irradiated; wherein said radiation operational parameters comprise a delay in curing radiation source activation following ink droplet (100) ejection, and at least one of: intensity level of the curing radiation source (116, 126), profile of the irradiation intensity, duration of the irradiation operation.

2. The method of claim 1, wherein said plurality of image elements (52, 54, 56) comprises at least two different ones of: a continuous tone element (52), a uniform tinted and solid element (52), a color element, a text element (56) and a line art element (56).

3. The method of claim 1, wherein said type of the given image element (52, 54, 56) to be irradiated determines said delay in said source (116, 126) activation.

4. The method of claim 1, wherein said type of the given image element (52, 54, 56) to be irradiated determines said intensity level of said source (116, 126).

5. The method of claim 1, wherein said type of the given image element (52, 54, 56) to be irradiated determines said duration of irradiation action.

6. The method of claim 1, wherein said type of the given image element (52, 54, 56) to be irradiated determines said intensity profile.

7. The method of claim 1, wherein said type of the given image element (52, 54, 56) to be irradiated determines the delay in said source (116, 126) activation, an intensity level of said source (116, 126), a duration of said irradiation operation, and an intensity profile.

8. The method of claim 1, wherein the type of the given image element to be irradiated sets the delay in said source (116, 126) activation, an intensity level of said source (116, 126), a duration of said irradiation operation, and an intensity profile.

9. The method of claim 1, wherein the digital form (data) of said type of the given image element (52, 54, 56) to be irradiated controls said source (116, 126) operational parameters.

10. The method of claim 1, wherein said curing radiation source (116, 126) comprises one or more of: at least one ultraviolet radiation emitter, at least one visible radiation emitter, at least one infra-red radiation emitter.

11. The method of claims 1 and 9, wherein the at least one ultraviolet emitter comprises at least two ultraviolet emitters having different wavelengths to each other.

12. The method of claims 1 and 9, wherein the at least one of infra-red emitter comprises at least two infra-red emitters having different wavelengths to each other.

13. The method of claims 1 and 10-12, wherein said radiation source (116) is a linear array of individually addressable radiation emitters (144).

14. The method of claims 1 and 10-12, wherein said radiation source (116) comprises a two-dimensional array of individually addressable radiation emitters (144).

15. The method of claim 1, wherein said type of the given image element (52, 54, 56) to be irradiated sets said radiation source (116, 126) to provide said curing radiation only to the ink covered portions of said image.

16. A method of claim 1, comprising depositing droplets (100) of ink onto a substrate (50) to form at least one row of pixels comprising different types of image elements (52, 54, 56), characterized in that a curing radiation scanning beam (130) scans said row of pixels (52, 54, 56) to be cured, and wherein analysis of the digital data of the image element to be printed controls a selection of operational parameters of said radiation beam (130).

17. An apparatus (98) comprising: an inkjet print head (70) to eject droplets (100) of ink onto a substrate to form an image comprising at least two different types of image elements (52, 54, 56); a curing radiation source (116, 26) to irradiate said image elements by radiation in accordance with operational parameters, characterized in that the apparatus further comprises a feature (72) to set the operational parameters based on the type of a given image element (52, 54, 56) to be irradiated; wherein said radiation operational parameters comprise delay in curing radiation source activation following ink droplet (100) ejection, and at least one of: intensity level of the curing radiation source (116, 126), profile of the irradiation intensity, duration of the irradiation operation .

18. The apparatus (98) of claim 17, wherein said feature (72) is to analyze the digital form (data) of said type of the image elements and to set the operational parameters based on the digital form (data) of said type of the given image element to be irradiated.

19. The apparatus (98) of claim 17, wherein said feature (72) comprises one of: software elements, hardware elements, and a combination of software elements and hardware elements.

20. The apparatus (98) of claim 17, wherein said source (116, 126) is rigidly connected with said print head (70).

21. The apparatus (98) of claim 17, wherein said radiation source (116, 126) is configured to move, and movement of the radiation source is synchronized with movement of said print head (70).

22. The apparatus (98) of claims 17 and 20-21, wherein said radiation source (116, 126) is one of: at least one UV LED, at least one Visible LED, at least one IR LED, a UV laser diode, an IR laser diode, a combination of UV and IR radiation emitters;
wherein the at least one ultraviolet emitter comprises at least two ultraviolet emitters having different wavelengths to each other, and
wherein the at least one infra-red emitter comprises at least two infra-red emitters having different wavelengths to each other.

23. The apparatus (98) of claims 17 and 20-22, wherein said radiation source (116) comprises a two-dimensional array of individually addressable radiation emitters (144), extended along the print head (70) scanning direction, and has image forming optics, said optics enabling irradiation of single droplet (100).

24. The apparatus (98) of claim 17, wherein said radiation source (126) comprises a scanning beam (130).

25. The apparatus (98) of claim 17, wherein said feature (72) controls said radiation source (116, 126).

26. A method of claim 1, characterized in that ink droplets (100) spread is controlled by curing radiation operational parameters dependent on the type of said given image element (52, 54, 56) to be irradiated such that said droplets (100) form on said substrate spots (108, 110, 112) having dimensions and overlaps which are variable in dependence on image element type.

27. The method of claim 26, wherein said plurality of image elements (52, 54, 56) comprises continuous tone elements (52), uniform tinted and solid elements (52), color elements, text (56) and line art (54) elements and a combination of them.

28. The apparatus (98) of claim 17 comprising: a control computer (74).

29. The apparatus (98) of claim 28, wherein said source (116) of curing radiation is one of a group of a linear array of radiation emitters and a two-dimensional array of radiation emitters (144).

30. The apparatus (98) of claims 28 and 29, wherein each of the radiation emitters (144) of said arrays is individually addressable.

31. The apparatus (98) of claims 28 and 29, wherein said feature (72) controls each of said individually addressable radiation emitters (144) within said arrays.

32. The apparatus of claim 28, wherein said control of each of said individually addressable radiation emitters (144) includes a plurality of said emitter (144) operational parameters.

Ansprüche

1. Verfahren zum Steuern einer Druckbildqualität, umfassend ein Ausstoßen von Tröpfchen (100) aus Tinte auf ein Substrat (50), um mehrere Bildelemente (52, 54, 56), umfassend Bildelemente von wenigstens zwei verschiedenen Arten, auszubilden, wobei die mehreren Bildelemente ein Bild ausbilden; dadurch gekennzeichnet, dass die Ausbreitung der Tintentröpfchen (100) durch Bestrahlen der Bildelemente durch Aushärtungsstrahlung gesteuert wird, wobei die Aushärtungsstrahlung durch Betriebsparameter, eingestellt auf der Grundlage der Art eines bestimmten zu bestrahlenden Bildelements (52, 54, 56), gesteuert wird; wobei die Strahlungsbetriebsparameter Folgendes umfassen: eine Verzögerung der Aktivierung einer Aushärtungsstrahlungsquelle nach dem Ausstoßen eines Tintentröpfchens (100) sowie: eine Intensitätsstufe der Aushärtungsstrahlungsquelle (116, 126), ein Profil der Strahlungsintensität und/oder eine Dauer des Bestrahlungsvorgangs.

2. Verfahren nach Anspruch 1, wobei die mehreren Bildelemente (52, 54, 56) wenigstens zwei verschiedene der Folgenden umfassen: ein Halbtonelement (52), ein einheitlich gefärbtes und durchgängiges Element (52), ein Farbelement, ein Textelement (56) und ein Line-Art-Element (56).

3. Verfahren nach Anspruch 1, wobei die Art des bestimmten zu bestrahlenden Bildelements (52, 54, 56) die Verzögerung der Aktivierung der Quelle (116, 126) bestimmt.

4. Verfahren nach Anspruch 1, wobei die Art des bestimmten zu bestrahlenden Bildelements (52, 54, 56) die Intensitätsstufe der Quelle (116, 126) bestimmt.

5. Verfahren nach Anspruch 1, wobei die Art des bestimmten zu bestrahlenden Bildelements (52, 54, 56) die Dauer der Bestrahlungsmaßnahme bestimmt.

6. Verfahren nach Anspruch 1, wobei die Art des bestimmten zu bestrahlenden Bildelements (52, 54, 56) das Intensitätsprofil bestimmt.

7. Verfahren nach Anspruch 1, wobei die Art des bestimmten zu bestrahlenden Bildelements (52, 54, 56) die Verzögerung der Aktivierung der Quelle (116, 126), eine Intensitätsstufe der Quelle (116, 126), eine Dauer des Bestrahlungsvorgangs und ein Intensitätsprofil bestimmt.

8. Verfahren nach Anspruch 1, wobei die Art des bestimmten zu bestrahlenden Bildelements die Verzögerung der Aktivierung der Quelle (116, 126), eine Intensitätsstufe der Quelle (116, 126), eine Dauer des Bestrahlungsvorgangs und ein Intensitätsprofil einstellt.

9. Verfahren nach Anspruch 1, wobei die digitale Form (Daten) der Art des zu bestrahlenden Bildelements (52, 54, 56) die Betriebsparameter der Quelle (116, 126) steuert.

10. Verfahren nach Anspruch 1, wobei die Aushärtungsstrahlungsquelle (116, 126) eines oder mehrere der Folgenden umfasst: wenigstens einen Emitter für Ultraviolettstrahlung, wenigstens einen Emitter für sichtbare Strahlung, wenigstens einen Emitter für Infrarotstrahlung.

11. Verfahren nach Anspruch 1 und 9, wobei der wenigstens eine Ultraviolettemitter wenigstens zwei Ultraviolettemitter mit voneinander verschiedenen Wellenlängen umfasst.

12. Verfahren nach Anspruch 1 und 9, wobei der wenigstens eine Infrarotemitter wenigstens zwei Infrarotemitter mit voneinander verschiedenen Wellenlängen umfasst.

13. Verfahren nach Anspruch 1 und 10-12, wobei es sich bei der Strahlungsquelle (116) um eine lineare Anordnung von individuell adressierbaren Strahlungsemittern (144) handelt.

14. Verfahren nach Anspruch 1 und 10-12, wobei die Strahlungsquelle (116) eine zweidimensionale Anordnung von individuell adressierbaren Strahlungsemittern (144) umfasst.

15. Verfahren nach Anspruch 1, wobei die Art des bestimmten zu bestrahlenden Bildelements (52, 54, 56) die Strahlungsquelle (116, 126) einstellt, um die Aushärtungsstrahlung nur an die mit Tinte bedeckten Abschnitte des Bildes bereitzustellen.

16. Verfahren nach Anspruch 1, umfassend ein Ablagern von Tröpfchen (100) aus Tinte auf ein Substrat (50), um wenigstens eine Reihe von Pixeln, umfassend unterschiedliche Arten von Bildelementen (52, 54, 56), auszubilden, dadurch gekennzeichnet, dass ein Aushärtungsstrahlungsabtaststrahl (130) die Reihe von auszuhärtenden Pixeln (52, 54, 56) abtastet, und wobei eine Analyse der digitalen Daten des zu druckenden Bildelements eine Auswahl von Betriebsparametern des Abtaststrahls (130) steuert.

17. Vorrichtung (98), umfassend: einen Tintenstrahldruckkopf (70), zum Ausstoßen von Tröpfchen (100) aus Tinte auf ein Substrat, um ein Bild, das wenigstens zwei unterschiedliche Arten von Bildelementen (52, 54, 56) umfasst, auszubilden; eine Aushärtungsstrahlungsquelle (116, 26) zum Bestrahlen der Bildelemente durch Strahlung gemäß Betriebsparametern, dadurch gekennzeichnet, dass die Vorrichtung ferner ein Merkmal (72) zum Einstellen der Betriebsparameter auf der Grundlage der Art eines bestimmten zu bestrahlenden Bildelements (52, 54, 56) umfasst; wobei die Strahlungsbetriebsparameter Folgendes umfassen: eine Verzögerung der Aktivierung einer Aushärtungsstrahlungsquelle nach dem Ausstoßen eines Tintentröpfchens (100) sowie: eine Intensitätsstufe der Aushärtungsstrahlungsquelle (116, 126), ein Profil der Strahlungsintensität und/oder eine Dauer des Bestrahlungsvorgangs.

18. Vorrichtung (98) nach Anspruch 17, wobei das Merkmal (72) zum Analysieren der digitalen Form (Daten) der Art der Bildelemente und zum Einstellen der Betriebsparameter auf der Grundlage der digitalen Form (Daten) der Art des bestimmten zu bestrahlenden Bildelements vorgesehen ist.

19. Vorrichtung (98) nach Anspruch 17, wobei das Merkmal (72) eines der Folgenden umfasst: Softwareelemente, Hardwareelemente und eine Kombination aus Softwareelementen und Hardwareelementen.

20. Vorrichtung (98) nach Anspruch 17, wobei die Quelle (116, 126) starr mit dem Druckkopf (70) verbunden ist.

21. Vorrichtung (98) nach Anspruch 17, wobei die Strahlungsquelle (116, 126) konfiguriert ist, sich zu bewegen, und eine Bewegung der Strahlungsquelle mit einer Bewegung des Druckkopfs (70) synchronisiert ist.

22. Vorrichtung (98) nach Anspruch 17 und 20-21, wobei die Strahlungsquelle (116, 126) eines der Folgenden ist: wenigstens eine Leuchtdiode für UV, wenigstens eine Leuchtdiode für sichtbares Licht, wenigstens eine Leuchtdiode für IR, eine UV-Laserdiode, eine IR-Laserdiode, eine Kombination aus UV- und IR-Strahlungsemittern;
wobei der wenigstens eine Ultraviolettemitter wenigstens zwei Ultraviolettemitter mit voneinander verschiedenen Wellenlängen umfasst, und
wobei der wenigstens eine Infrarotemitter wenigstens zwei Infrarotemitter mit voneinander verschiedenen Wellenlängen umfasst.

23. Vorrichtung (98) nach Anspruch 17 und 20-22, wobei die Strahlungsquelle (116) eine zweidimensionale Anordnung aus individuell adressierbaren Strahlungsemittern (144) umfasst, entlang der Abtastrichtung des Druckkopfs (70) erweitert ist und bilderzeugende Optik aufweist, wobei die Optik eine Bestrahlung eines einzelnen Tröpfchens (100) ermöglicht.

24. Vorrichtung (98) nach Anspruch 17, wobei die Bestrahlungsquelle (126) einen Abtaststrahl (130) umfasst.

25. Vorrichtung (98) nach Anspruch 17, wobei das Merkmal (72) die Strahlungsquelle (116, 126) steuert.

26. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Ausbreitung von Tintentröpfchen (100) durch Aushärtungsstrahlungsbetriebsparameter, die von der Art des bestimmten zu bestrahlenden Bildelements (52, 54, 56) abhängig sind, gesteuert wird, sodass die Tröpfchen (100) auf dem Substrat Punkte (108, 110, 112) mit Abmessungen und Überschneidungen, die abhängig von der Bildelementart unterschiedlich sind, ausbilden.

27. Verfahren nach Anspruch 26, wobei die mehreren Bildelemente (52, 54, 56) Halbtonelemente (52), einheitlich gefärbte und durchgängige Elemente (52), Farbelemente, Elemente aus Text (56) und aus Line-Art (54) sowie eine Kombination daraus umfassen.

28. Vorrichtung (98) nach Anspruch 17, umfassend: einen Steuerrechner (74).

29. Vorrichtung (98) nach Anspruch 28, wobei die Quelle (116) der Aushärtungsstrahlung eines aus einer Gruppe aus einer linearen Anordnung aus Strahlungsemittern und einer zweidimensionalen Anordnung aus Strahlungsemittern (144) ist.

30. Vorrichtung (98) nach Anspruch 28 und 29, wobei jeder der Strahlungsemitter (144) der Anordnungen individuell adressierbar ist.

31. Vorrichtung (98) nach Anspruch 28 und 29, wobei das Merkmal (72) jeden der individuell adressierbaren Strahlungsemitter (144) in den Anordnungen steuert.

32. Vorrichtung nach Anspruch 28, wobei die Steuerung jedes der individuell adressierbaren Strahlungsemitter (144) mehrere der Betriebsparameter des Emitters (144) enthält.

Revendications

1. Procédé de contrôle de la qualité d'image imprimée comprenant l'éjection de gouttelettes (100) d'encre sur un substrat (50) pour former une pluralité d'éléments d'image (52, 54, 56) comprenant des éléments d'image d'au moins deux types différents, ladite pluralité d'éléments d'image formant une image ;
caractérisé en ce que l'étalement desdites gouttelettes d'encre (100) est commandé en irradiant lesdits éléments d'image par un rayonnement de durcissement, ledit rayonnement de durcissement étant commandé par des paramètres opérationnels établis sur la base du type d'un élément d'image donné (52, 54, 56) à irradier ;
dans lequel lesdits paramètres opérationnels de rayonnement comprennent un retard dans l'activation de la source de rayonnement de durcissement après l'éjection de gouttelettes d'encre (100), et au moins l'un des éléments parmi : le niveau d'intensité de la source de rayonnement de durcissement (116, 126), le profil de l'intensité d'irradiation, la durée de l'opération d'irradiation.

2. Procédé selon la revendication 1, dans lequel ladite pluralité d'éléments d'image (52, 54, 56) comprend au moins deux éléments différents parmi : un élément à tons continus (52), un élément plein et uniformément teinté (52), un élément en couleur, un élément de texte (56) et un élément de dessin au trait (56).

3. Procédé selon la revendication 1, dans lequel ledit type de l'élément d'image donné (52, 54, 56) à irradier détermine ledit retard dans l'activation de ladite source (116, 126).

4. Procédé selon la revendication 1, dans lequel ledit type de l'élément d'image donné (52, 54, 56) à irradier détermine ledit niveau d'intensité de ladite source (116, 126).

5. Procédé selon la revendication 1, dans lequel ledit type de l'élément d'image donné (52, 54, 56) à irradier détermine ladite durée de l'action d'irradiation.

6. Procédé selon la revendication 1, dans lequel ledit type de l'élément d'image donné (52, 54, 56) à irradier détermine ledit profil d'intensité.

7. Procédé selon la revendication 1, dans lequel ledit type de l'élément d'image donné (52, 54, 56) à irradier détermine le retard dans l'activation de ladite source (116, 126), un niveau d'intensité de ladite source (116, 126), une durée de ladite opération d'irradiation, et un profil d'intensité.

8. Procédé selon la revendication 1, dans lequel le type de l'élément d'image donné à irradier établit le retard dans l'activation de ladite source (116, 126), un niveau d'intensité de ladite source (116, 126), une durée de ladite opération d'irradiation, et un profil d'intensité.

9. Procédé selon la revendication 1, dans lequel la forme numérique (données) dudit type de l'élément d'image donné (52, 54, 56) à irradier commande les paramètres opérationnels de ladite source (116, 126).

10. Procédé selon la revendication 1, dans lequel ladite source de rayonnement de durcissement (116, 126) comprend l'un ou plusieurs des éléments parmi : au moins un émetteur de rayonnement ultraviolet, au moins un émetteur de rayonnement visible, au moins un émetteur de rayonnement infrarouge.

11. Procédé selon les revendications 1 et 9, dans lequel ledit émetteur d'ultraviolets comprend au moins deux émetteurs d'ultraviolets ayant différentes longueurs d'onde l'un par rapport à l'autre.

12. Procédé selon les revendications 1 et 9, dans lequel ledit émetteur d'infrarouges comprend au moins deux émetteurs d'infrarouges ayant différentes longueurs d'onde l'un par rapport à l'autre.

13. Procédé selon les revendications 1 et 10 à 12, dans lequel ladite source de rayonnement (116) est un réseau linéaire d'émetteurs de rayonnement adressables individuellement (144).

14. Procédé selon les revendications 1 et 10 à 12, dans lequel ladite source de rayonnement (116) comprend un réseau bidimensionnel d'émetteurs de rayonnement adressables individuellement (144).

15. Procédé selon la revendication 1, dans lequel ledit type de l'élément d'image donné (52, 54, 56) à irradier établit ladite source de rayonnement (116, 126) pour fournir ledit rayonnement de durcissement uniquement aux parties recouvertes d'encre de ladite image.

16. Procédé selon la revendication 1, comprenant le dépôt de gouttelettes (100) d'encre sur un substrat (50) pour former au moins une rangée de pixels comprenant différents types d'éléments d'image (52, 54, 56), caractérisé en ce qu'un faisceau de balayage de rayonnement de durcissement (130) balaie ladite rangée de pixels (52, 54, 56) à durcir, et dans lequel l'analyse des données numériques de l'élément d'image à imprimer commande une sélection de paramètres opérationnels dudit faisceau de rayonnement (130).

17. Appareil (98) comprenant : une tête d'impression à jet d'encre (70) pour éjecter des gouttelettes (100) d'encre sur un substrat pour former une image comprenant au moins deux types différents d'éléments d'image (52, 54, 56) ; une source de rayonnement de durcissement (116, 26) pour irradier lesdits éléments d'image par rayonnement conformément à des paramètres opérationnels, caractérisé en ce que l'appareil comprend en outre une caractéristique (72) pour établir les paramètres opérationnels sur la base du type d'un élément d'image donné (52, 54, 56) à irradier ; dans lequel lesdits paramètres opérationnels de rayonnement comprennent un retard dans l'activation de la source de rayonnement de durcissement après l'éjection de gouttelettes d'encre (100), et au moins l'un des éléments parmi : le niveau d'intensité de la source de rayonnement de durcissement (116, 126), le profil de l'intensité d'irradiation, la durée de l'opération d'irradiation.

18. Appareil (98) selon la revendication 17, dans lequel ladite caractéristique (72) consiste à analyser la forme numérique (données) dudit type des éléments d'image et à établir les paramètres opérationnels sur la base de la forme numérique (données) dudit type d'élément d'image donné à irradier.

19. Appareil (98) selon la revendication 17, dans lequel ladite caractéristique (72) comprend l'un des éléments parmi : des éléments logiciels, des éléments matériels, et une combinaison d'éléments logiciels et d'éléments matériels.

20. Appareil (98) selon la revendication 17, dans lequel ladite source (116, 126) est reliée rigidement à ladite tête d'impression (70).

21. Appareil (98) selon la revendication 17, dans lequel ladite source de rayonnement (116, 126) est conçue pour se déplacer, et le mouvement de la source de rayonnement est synchronisé avec le mouvement de ladite tête d'impression (70).

22. Appareil (98) selon les revendications 17 et 20 à 21, dans lequel ladite source de rayonnement (116, 126) est l'un des éléments parmi : au moins une LED UV, au moins une LED visible, au moins une LED IR, une diode laser UV, une diode laser IR, une combinaison d'émetteurs de rayonnement UV et IR ;
dans lequel ledit émetteur d'ultraviolets comprend au moins deux émetteurs d'ultraviolets ayant différentes longueurs d'onde l'un par rapport à l'autre, et
dans lequel ledit émetteur d'infrarouges comprend au moins deux émetteurs d'infrarouges ayant différentes longueurs d'onde l'un par rapport à l'autre.

23. Appareil (98) selon les revendications 17 et 20 à 22, dans lequel ladite source de rayonnement (116) comprend un réseau bidimensionnel d'émetteurs de rayonnement adressables individuellement (144), étendu le long de la direction de balayage de la tête d'impression (70), et a une optique de formation d'image, ladite optique permettant l'irradiation de gouttelettes uniques (100).

24. Appareil (98) selon la revendication 17, dans lequel ladite source de rayonnement (126) comprend un faisceau de balayage (130).

25. Appareil (98) selon la revendication 17, dans lequel ladite caractéristique (72) commande ladite source de rayonnement (116, 126).

26. Procédé selon la revendication 1, caractérisé en ce que l'étalement de gouttelettes d'encre (100) est commandé par des paramètres opérationnels de rayonnement de durcissement selon le type dudit élément d'image donné (52, 54, 56) à irradier de sorte que lesdites gouttelettes (100) forment sur ledit substrat des points (108, 110, 112) ayant des dimensions et des chevauchements variables en fonction du type d'élément d'image.

27. Procédé selon la revendication 26, dans lequel ladite pluralité d'éléments d'image (52, 54, 56) comprend des éléments à tons continus (52), des éléments pleins et uniformément teintés (52), des éléments en couleur, des éléments de texte (56) et de dessin au trait (54) et une combinaison de ceux-ci.

28. Appareil (98) selon la revendication 17 comprenant : un ordinateur de commande (74).

29. Appareil (98) selon la revendication 28, dans lequel ladite source (116) de rayonnement de durcissement est l'un des éléments parmi un groupe constitué d'un réseau linéaire d'émetteurs de rayonnement et d'un réseau bidimensionnel d'émetteurs de rayonnement (144).

30. Appareil (98) selon les revendications 28 et 29, dans lequel chacun des émetteurs de rayonnement (144) desdits réseaux est adressable individuellement.

31. Appareil (98) selon les revendications 28 et 29, dans lequel ladite caractéristique (72) commande chacun desdits émetteurs de rayonnement adressables individuellement (144) dans lesdits réseaux.

32. Appareil selon la revendication 28, dans lequel ladite commande de chacun desdits émetteurs de rayonnement adressables individuellement (144) comprend une pluralité de paramètres opérationnels dudit émetteur (144).

Drawing